- Email: [email protected]
Thermal performance of juvenile Atlantic salmon (Salmo salar L.) of Baltic Sea origin
ARTICLE IN PRESS
Journal of Thermal Biology 31 (2006) 243–246 www.elsevier.com/locate/jtherbio
Thermal performance of juvenile Atlantic salmon (Salmo salar L.) of Baltic Sea origin S. Larsson, I. Berglund1 Department of Aquaculture, Swedish University of Agricultural Sciences, SE-901 83 Umea˚, Sweden Received 6 July 2005; accepted 4 October 2005
Abstract 1. The effect of temperature on food intake, growth and energetic growth efficiency of Atlantic salmon of Baltic Sea origin was studied in tanks. 2. Energetic growth efficiency, optimum temperature for growth and thermal limits for feeding and growth were similar to those reported for Atlantic salmon populations from Norway. 3. The maximum growth capacity of Baltic salmon in this study was, however, considerably higher than those reported for Atlantic populations from Norway. 4. The comparably higher growth capacity of Baltic salmon might be an adaptation to local factors or due to genotypic difference between Baltic and Atlantic salmon. r 2005 Elsevier Ltd. All rights reserved. Keywords: Temperature; Feeding; Growth rate; Thermal adaptation; Food consumption; Baltic salmon
Atlantic salmon (Salmo salar L.) are found throughout the North Atlantic Ocean, including the coast of Norway and the Baltic Sea (Klemetsen et al., 2003). It has been suggested that the Atlantic salmon inhabiting the Baltic Sea (from here on denoted as Baltic salmon) are genetically distinct from those inhabiting the Atlantic Ocean and that Baltic salmon colonised the Baltic Sea through a northeast link to the Barents Sea and not from the Atlantic Ocean, via the Danish strait (Nilsson et al., 2001). In contrast to the majority of Atlantic salmon populations, Baltic salmon do not migrate to common-feeding areas in the North Atlantic Ocean, opting instead to stay in the Baltic Sea where temperatures and salinity are different from the North Atlantic Ocean. Hence, Baltic salmon seem to be distinct from Atlantic populations with regards genotype and adult-feeding ecology. Overall, the thermal performance of Atlantic salmon is reasonably well studied. For Corresponding author. Tel.: +46 90 7868394; fax: +46 90 123729.
E-mail address: [email protected] (S. Larsson). Current address: National Board of Fisheries, Box 423, SE-401 26 Go¨teborg, Sweden. 1
0306-4565/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jtherbio.2005.10.002
instance, data on maximum growth and food consumption of Atlantic salmon parr from five Norwegian rivers were recently published (Jonsson et al., 2001). However, corresponding data on Baltic salmon is poor. This study examines food intake, growth rate and growth efficiency of Baltic salmon in relation to temperature and compares the results to thermal performance of Atlantic salmon populations originating from the Atlantic Ocean. In this study, the thermal performance of Baltic salmon from the river Vindela¨lven, Sweden (N163, E120) was studied at 8 different temperatures in two separate trials. All fish used were the progeny of naturally spawned parents. Before the start of the trials, fish were acclimatised to individual tanks for 10 days at 11–12 1C, with food being provided in excess. Thereafter, the experimental temperatures (5, 9, 10, 15, 18, 20, 22 and 24 1C) were applied by decreasing or increasing the temperature at approximately 1 1C/h. The fish were kept at the experimental temperatures for 4 days, before their initial fork length (nearest mm) and weight (nearest 0.01 g) were recorded. During the trials, each lasting 14 days, fish were fed commercial dry food pellets (Skretting AS) in excess with automatic feeders
ARTICLE IN PRESS 244
S. Larsson, I. Berglund / Journal of Thermal Biology 31 (2006) 243–246
Table 1 Summary of experiments on growth and food intake in Baltic Atlantic salmon from Vindela¨lven and parameter estimates of Ratkowsky models (see Forseth et al., 2001) Initial weights (g)
Temperatures (1C)
N
c
TM
TL
TU
R2
Growth 8.5 37.2
5, 9, 15, 18, 20, 22, 24 5, 9, 10, 15, 18, 20, 22, 24
27 51
9.3 (0.40) 4.4 (0.38)
18.4 (0.44) 17.5 (1.15)
4.1 (0.46) 3.7 (1.17)
24.8 (0.20) 24.3 (0.47)
90.3 48.0
Energy intake 37.2
5, 9, 10, 15, 18, 20, 22, 24
51
0.6 (0.04)
18.6 (0.87)
2.40 (1.10)
25.5 (0.89)
52.5
c is the standardized growth rate or food intake of a 1-g fish at the optimum temperature for growth. TM is the optimum temperature for growth or food intake. TL and TU are the lower and upper temperature limits for growth or food intake. Values within brackets are bootstrap standard errors (Efron and Tibshirani, 1993). Note: Parameter estimates and bootstrap standard errors are shown.
(Petmate 14). At the end of the growth period, fork length and weight were recorded. The oxygen concentration was throughout the study kept at 95–100% saturation by aeration and light intensities at the surface of the tanks were ca. 15 and 0.5 lx at day and night, respectively. Fish were reared singly in plastic tanks arranged in temperature control systems with partly re-circulated tap water according to the protocol of Larsson and Berglund (1998). In the first trial (N ¼ 27, initial mean size ¼ 8.5 g, 11 l tanks), only growth rate was estimated. In the second trial (N ¼ 51, initial mean size ¼ 37.2 g, 67 l tanks), growth rate, food intake and energetic growth efficiency was estimated (Table 1). To obtain food intake data, the number of pellets delivered at each feeding was recorded and before each subsequent feeding uneaten pellets (at least 20% of the ration) and faeces were removed by suction and all uneaten pellets were counted (for details see Larsson and Berglund, 2005). A re-parameterised version of a curvlinear model originally used for the growth of bacterial in culture by Ratkowsky et al. (1983), used to model growth of Atlantic salmon (Forseth et al., 2001; Jonsson et al., 2001) and Arctic charr (Salvelinus alpinus L.) (Larsson et al., 2005), was applied to the food intake and growth data. The reparameterised Ratkowsky model consists of biologically meaningful parameters: lower (TL) and upper (TU) critical temperatures for growth (or food intake), temperature for optimum growth (or food intake) (TM), growth of a 1 g fish at the optimum temperature (c) and standardized massspecific growth rate (9). The overall thermal performance of Baltic salmon in this study was in accordance with the performance of Atlantic salmon populations studied by Jonsson et al. (2001). The optimum temperature for growth of Baltic salmon was found to be 18.4 1C (70.44SE) and 17.5 1C (71.15SE) for small (initial mean size: 8.5 g) and large (initial mean size: 37.2 g) fish, respectively (Fig. 1, Table 1.), which in general corresponds to those of Atlantic salmon populations (range: 16.3–20.0 1C, Jonsson et al., 2001). The lower temperature limit for growth of Baltic salmon (small: 4.1 1C70.46 SE, large: 3.7 1C71.17 SE) was slightly lower
than for the Atlantic populations (range: 4.9 1C to 10.7 1C, Jonsson et al., 2001). Similarly, the relationship of temperature to food intake and growth efficiency did not differ between Baltic salmon and Atlantic salmon. The optimum temperature for food intake in Atlantic salmon populations ranged from 17.0 to 21.6 1C. For the larger Baltic salmon in the second trial, food intake was maximised at 18.6 1C (70.87SE). The lower limit for food intake (2.4 1C71.1SE) of Baltic salmon was on the lower end of the range for Atlantic salmon (range: 2.1–7.1 1C). In this study, there was no distinct peak in the relationship between growth efficiency and temperature and therefore, no optimum temperature for growth efficiency could be estimated. However, in accordance with the study by Jonsson et al. (2001), maximum growth efficiency (48% at 10 1C) was observed at a temperature lower than the optimum temperature for growth. The outstanding difference between Baltic in this study and Atlantic salmon in the study by Jonsson et al. (2001) was the higher standardised maximum growth rate of Baltic salmon. The smaller Baltic salmon in the first trial of this study had a c-value (growth rate of a 1-g fish at the optimum temperature) of 9.3%70.40SE (Table 1). This was about three times higher or more than the recorded mean growth rates (range: 2.04–3.25%) of the Atlantic salmon in the study by Jonsson et al. (2001). This difference is remarkable. The growth rate of salmonids is, however, known to vary with fish size (Brett, 1979) and season (Smith et al., 1993; Nordgarden et al., 2003). The smaller salmon in this study was of similar size (initial mean size: this study ¼ 8.5 g; Jonsson et al. (2001) ¼ 2.25–11.45 g), excluding size as an explanatory factor. The time of season differed, however, slightly. The smaller fish in this study was tested in June and the salmon in the study by Jonsson et al. (2001) in July–October. This might partly explain the difference in growth rate. Indeed, the larger Baltic salmon of the second trial in this study, reared in December–January, showed significantly lower growth rates (4.4%70.38SE) than the smaller salmon in the first trial (reared in June), suggesting that Baltic salmon exhibit large seasonal variation in growth rate.
ARTICLE IN PRESS S. Larsson, I. Berglund / Journal of Thermal Biology 31 (2006) 243–246
12 10
Ω (%)
8 6 4 2 0
0
2
4
6
8
10
12
14
16
18
20
22
24
0
2
4
6
8
10
12
14
16
18
20
22
24
0.8
Φ
0.6 0.4 0.2 0.0
Growth efficiency (%)
50
245
Larsson et al. (2005), Arctic charr reared in groups showed comparable growth rates to charr reared singly and Baltic salmon from river Neva (Koskela et al., 1997), despite being reared in groups, showed higher growth rates than the Atlantic salmon studied by Jonsson et al. (2001). This study suggests that Atlantic and Baltic salmon are generally similar in thermal performance. No major differences in lower (TL) and upper (TU) critical temperatures for growth and temperature for optimum growth (TM) was found between Baltic salmon in this study and Atlantic salmon from five populations in Norway (Jonsson et al., 2001). However, it appears that the growth capacity is significantly higher in Baltic salmon. The reason for this is still to be examined but variation in growth potential might be related to adaptation to local environment, lifehistory characteristics and diets (e.g. adult-feeding areas). Alternatively, the differences in growth rates between Baltic and Atlantic salmon are a result of their different genotypes (Nilsson et al., 2001) and the Baltic and the Atlantic salmon should then be considered as separate entities. Financial support was given by the European Commission under the FAIR Programme (Contract No. CT95-0009), by the Swedish Forestry and Agricultural Research Council to IB and by the Oscar and Lilly Lamm Foundation, the CF Lundstro¨m foundation and the Carl Trygger foundation to SL.
40 30 20 10 0
References 0
2
4
6
8
10
12 14
16
18
20
22
24
Temperature (°C) Fig. 1. Standardised growth rate O (%), standardised energy intake F (kJ g1) and energetic growth efficiency (%) of Baltic Atlantic salmon from Vindela¨lven (Sweden), in relation to temperature. Data from small (initial mean weight ¼ 8.5 g) parr tested in June (only growth data) and large (initial mean weight ¼ 37 g) parr tested in December–January are indicated with open and solid circles, respectively. Solid lines show fitted Ratkowsky models (see Forseth et al., 2001). Observed means72 SE are shown (for parameter estimates see Table 1).
To our knowledge, there is only one previous study of Baltic salmon growth and food intake in relation to temperature. Koskela et al. (1997) found the optimum temperatures for growth and food intake of salmon from the river Neva (601N, 311E) to be 15.6 and 17.8 1C, respectively, which is lower than for the Atlantic salmon (Jonsson et al., 2001) and the Baltic salmon in this study. The maximum growth rate for Neva River Baltic salmon (c ¼ 5.5% when standardised to a 1-g fish according to the protocol of Forseth et al., 2001) was considerably higher than for Atlantic salmon. A confounding factor might be that the Atlantic salmon in the study by Jonsson et al. (2001) were reared in groups while the Baltic salmon in this study and were reared singly. However, in a study by
Brett, J.R., 1979. Environmental Factors and Growth. Fish Physiology. Academic Press, New York, pp. 599–675. Efron, B., Tibshirani, R.J., 1993. An Introduction to the Bootstrap. Chapman & Hall, London. Forseth, T., Hurley, M.A., Jensen, A.J., Elliott, J.M., 2001. Functional models forgrowth and food consumption of Atlantic salmon parr, Salmo salar, from a Norwegian river. Freshwater Biol. 46, 173–186. Jonsson, B., Forseth, T., Jensen, A.J., Næsje, T.F., 2001. Thermal performance injuvenile Atlantic salmon, Salmo salar L. Funct. Ecol. 15, 701–711. Klemetsen, A., Amundsen, P.A., Dempson, J.B., Jonsson, B., Jonsson, N., O’Connell, M.F., Mortensen, E., 2003. Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus L.: a review of aspects of their life histories. Ecol. Freshwater Fish 12, 1–59. Koskela, J., Pirhonen, J., Jobling, M., 1997. Feed intake, growth rate and body composition of juvenile Baltic salmon exposed to different constant temperatures. Aquacult. Int. 5, 351–360. Larsson, S., Berglund, I., 1998. Growth and food consumption of 0+ Arctic charr fed pelleted or natural food at six different temperatures. J. Fish Biol. 52, 230–242. Larsson, S., Berglund, I., 2005. The effect of temperature on the energetic growth efficiency of Arctic charr (Salvelinus alpinus L.) from four Swedish populations. J. Therm. Biol. 30, 29–36. Larsson, S., Forseth, T., Berglund, I., Jensen, A.J., Na¨slund, I., Elliott, J.M., Jonsson, B., 2005. Thermal adaptation of Arctic charr: experimental studies of growth in eleven charr populations from Sweden, Norway and Britain. Freshwater Biol. 50, 353–368. Nilsson, J., Gross, R., Asplund, T., Dove, O., Jansson, H., Kelloniemi, J., Kohlmann, K., Loytynoja, A., Nielsen, E.E., Paaver, T., Primmer, C.R., Titov, S., Vasemagi, A., Veselov, A., Ost, T., Lumme, J., 2001.
ARTICLE IN PRESS 246
S. Larsson, I. Berglund / Journal of Thermal Biology 31 (2006) 243–246
Matrilinear phylogeography of Atlantic salmon (Salmo salar L.) in Europe and postglacial colonization of the Baltic. Mol. Ecol. 10, 89–102. Nordgarden, U., Oppedal, F., Taranger, G.L., Hemre, G.-I., Hansen, T., 2003. Seasonally changing metabolism in Atlantic salmon (Salmo salar L.) I— Growth and feed conversion ratio. Aquacult. Nutr. 9, 287–293.
Ratkowsky, D.A., Lowry, R.K., McMeekin, T.A., Stokes, A.N., Chandler, R.E., 1983. Model for bacterial culture growth rate throughout the entire biokenetic temperature ange. J. Bacteriol. 154, 1222–1226. Smith, I.P., Metcalfe, N.B., Huntingford, F.A., Kadri, S., 1993. Daily and seasonal patterns in the feeding-behavior of Atlantic salmon (Salmosalar L) in a sea cage. Aquaculture 117, 165–178.
Journal of Thermal Biology 31 (2006) 243–246 www.elsevier.com/locate/jtherbio
Thermal performance of juvenile Atlantic salmon (Salmo salar L.) of Baltic Sea origin S. Larsson, I. Berglund1 Department of Aquaculture, Swedish University of Agricultural Sciences, SE-901 83 Umea˚, Sweden Received 6 July 2005; accepted 4 October 2005
Abstract 1. The effect of temperature on food intake, growth and energetic growth efficiency of Atlantic salmon of Baltic Sea origin was studied in tanks. 2. Energetic growth efficiency, optimum temperature for growth and thermal limits for feeding and growth were similar to those reported for Atlantic salmon populations from Norway. 3. The maximum growth capacity of Baltic salmon in this study was, however, considerably higher than those reported for Atlantic populations from Norway. 4. The comparably higher growth capacity of Baltic salmon might be an adaptation to local factors or due to genotypic difference between Baltic and Atlantic salmon. r 2005 Elsevier Ltd. All rights reserved. Keywords: Temperature; Feeding; Growth rate; Thermal adaptation; Food consumption; Baltic salmon
Atlantic salmon (Salmo salar L.) are found throughout the North Atlantic Ocean, including the coast of Norway and the Baltic Sea (Klemetsen et al., 2003). It has been suggested that the Atlantic salmon inhabiting the Baltic Sea (from here on denoted as Baltic salmon) are genetically distinct from those inhabiting the Atlantic Ocean and that Baltic salmon colonised the Baltic Sea through a northeast link to the Barents Sea and not from the Atlantic Ocean, via the Danish strait (Nilsson et al., 2001). In contrast to the majority of Atlantic salmon populations, Baltic salmon do not migrate to common-feeding areas in the North Atlantic Ocean, opting instead to stay in the Baltic Sea where temperatures and salinity are different from the North Atlantic Ocean. Hence, Baltic salmon seem to be distinct from Atlantic populations with regards genotype and adult-feeding ecology. Overall, the thermal performance of Atlantic salmon is reasonably well studied. For Corresponding author. Tel.: +46 90 7868394; fax: +46 90 123729.
E-mail address: [email protected] (S. Larsson). Current address: National Board of Fisheries, Box 423, SE-401 26 Go¨teborg, Sweden. 1
0306-4565/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jtherbio.2005.10.002
instance, data on maximum growth and food consumption of Atlantic salmon parr from five Norwegian rivers were recently published (Jonsson et al., 2001). However, corresponding data on Baltic salmon is poor. This study examines food intake, growth rate and growth efficiency of Baltic salmon in relation to temperature and compares the results to thermal performance of Atlantic salmon populations originating from the Atlantic Ocean. In this study, the thermal performance of Baltic salmon from the river Vindela¨lven, Sweden (N163, E120) was studied at 8 different temperatures in two separate trials. All fish used were the progeny of naturally spawned parents. Before the start of the trials, fish were acclimatised to individual tanks for 10 days at 11–12 1C, with food being provided in excess. Thereafter, the experimental temperatures (5, 9, 10, 15, 18, 20, 22 and 24 1C) were applied by decreasing or increasing the temperature at approximately 1 1C/h. The fish were kept at the experimental temperatures for 4 days, before their initial fork length (nearest mm) and weight (nearest 0.01 g) were recorded. During the trials, each lasting 14 days, fish were fed commercial dry food pellets (Skretting AS) in excess with automatic feeders
ARTICLE IN PRESS 244
S. Larsson, I. Berglund / Journal of Thermal Biology 31 (2006) 243–246
Table 1 Summary of experiments on growth and food intake in Baltic Atlantic salmon from Vindela¨lven and parameter estimates of Ratkowsky models (see Forseth et al., 2001) Initial weights (g)
Temperatures (1C)
N
c
TM
TL
TU
R2
Growth 8.5 37.2
5, 9, 15, 18, 20, 22, 24 5, 9, 10, 15, 18, 20, 22, 24
27 51
9.3 (0.40) 4.4 (0.38)
18.4 (0.44) 17.5 (1.15)
4.1 (0.46) 3.7 (1.17)
24.8 (0.20) 24.3 (0.47)
90.3 48.0
Energy intake 37.2
5, 9, 10, 15, 18, 20, 22, 24
51
0.6 (0.04)
18.6 (0.87)
2.40 (1.10)
25.5 (0.89)
52.5
c is the standardized growth rate or food intake of a 1-g fish at the optimum temperature for growth. TM is the optimum temperature for growth or food intake. TL and TU are the lower and upper temperature limits for growth or food intake. Values within brackets are bootstrap standard errors (Efron and Tibshirani, 1993). Note: Parameter estimates and bootstrap standard errors are shown.
(Petmate 14). At the end of the growth period, fork length and weight were recorded. The oxygen concentration was throughout the study kept at 95–100% saturation by aeration and light intensities at the surface of the tanks were ca. 15 and 0.5 lx at day and night, respectively. Fish were reared singly in plastic tanks arranged in temperature control systems with partly re-circulated tap water according to the protocol of Larsson and Berglund (1998). In the first trial (N ¼ 27, initial mean size ¼ 8.5 g, 11 l tanks), only growth rate was estimated. In the second trial (N ¼ 51, initial mean size ¼ 37.2 g, 67 l tanks), growth rate, food intake and energetic growth efficiency was estimated (Table 1). To obtain food intake data, the number of pellets delivered at each feeding was recorded and before each subsequent feeding uneaten pellets (at least 20% of the ration) and faeces were removed by suction and all uneaten pellets were counted (for details see Larsson and Berglund, 2005). A re-parameterised version of a curvlinear model originally used for the growth of bacterial in culture by Ratkowsky et al. (1983), used to model growth of Atlantic salmon (Forseth et al., 2001; Jonsson et al., 2001) and Arctic charr (Salvelinus alpinus L.) (Larsson et al., 2005), was applied to the food intake and growth data. The reparameterised Ratkowsky model consists of biologically meaningful parameters: lower (TL) and upper (TU) critical temperatures for growth (or food intake), temperature for optimum growth (or food intake) (TM), growth of a 1 g fish at the optimum temperature (c) and standardized massspecific growth rate (9). The overall thermal performance of Baltic salmon in this study was in accordance with the performance of Atlantic salmon populations studied by Jonsson et al. (2001). The optimum temperature for growth of Baltic salmon was found to be 18.4 1C (70.44SE) and 17.5 1C (71.15SE) for small (initial mean size: 8.5 g) and large (initial mean size: 37.2 g) fish, respectively (Fig. 1, Table 1.), which in general corresponds to those of Atlantic salmon populations (range: 16.3–20.0 1C, Jonsson et al., 2001). The lower temperature limit for growth of Baltic salmon (small: 4.1 1C70.46 SE, large: 3.7 1C71.17 SE) was slightly lower
than for the Atlantic populations (range: 4.9 1C to 10.7 1C, Jonsson et al., 2001). Similarly, the relationship of temperature to food intake and growth efficiency did not differ between Baltic salmon and Atlantic salmon. The optimum temperature for food intake in Atlantic salmon populations ranged from 17.0 to 21.6 1C. For the larger Baltic salmon in the second trial, food intake was maximised at 18.6 1C (70.87SE). The lower limit for food intake (2.4 1C71.1SE) of Baltic salmon was on the lower end of the range for Atlantic salmon (range: 2.1–7.1 1C). In this study, there was no distinct peak in the relationship between growth efficiency and temperature and therefore, no optimum temperature for growth efficiency could be estimated. However, in accordance with the study by Jonsson et al. (2001), maximum growth efficiency (48% at 10 1C) was observed at a temperature lower than the optimum temperature for growth. The outstanding difference between Baltic in this study and Atlantic salmon in the study by Jonsson et al. (2001) was the higher standardised maximum growth rate of Baltic salmon. The smaller Baltic salmon in the first trial of this study had a c-value (growth rate of a 1-g fish at the optimum temperature) of 9.3%70.40SE (Table 1). This was about three times higher or more than the recorded mean growth rates (range: 2.04–3.25%) of the Atlantic salmon in the study by Jonsson et al. (2001). This difference is remarkable. The growth rate of salmonids is, however, known to vary with fish size (Brett, 1979) and season (Smith et al., 1993; Nordgarden et al., 2003). The smaller salmon in this study was of similar size (initial mean size: this study ¼ 8.5 g; Jonsson et al. (2001) ¼ 2.25–11.45 g), excluding size as an explanatory factor. The time of season differed, however, slightly. The smaller fish in this study was tested in June and the salmon in the study by Jonsson et al. (2001) in July–October. This might partly explain the difference in growth rate. Indeed, the larger Baltic salmon of the second trial in this study, reared in December–January, showed significantly lower growth rates (4.4%70.38SE) than the smaller salmon in the first trial (reared in June), suggesting that Baltic salmon exhibit large seasonal variation in growth rate.
ARTICLE IN PRESS S. Larsson, I. Berglund / Journal of Thermal Biology 31 (2006) 243–246
12 10
Ω (%)
8 6 4 2 0
0
2
4
6
8
10
12
14
16
18
20
22
24
0
2
4
6
8
10
12
14
16
18
20
22
24
0.8
Φ
0.6 0.4 0.2 0.0
Growth efficiency (%)
50
245
Larsson et al. (2005), Arctic charr reared in groups showed comparable growth rates to charr reared singly and Baltic salmon from river Neva (Koskela et al., 1997), despite being reared in groups, showed higher growth rates than the Atlantic salmon studied by Jonsson et al. (2001). This study suggests that Atlantic and Baltic salmon are generally similar in thermal performance. No major differences in lower (TL) and upper (TU) critical temperatures for growth and temperature for optimum growth (TM) was found between Baltic salmon in this study and Atlantic salmon from five populations in Norway (Jonsson et al., 2001). However, it appears that the growth capacity is significantly higher in Baltic salmon. The reason for this is still to be examined but variation in growth potential might be related to adaptation to local environment, lifehistory characteristics and diets (e.g. adult-feeding areas). Alternatively, the differences in growth rates between Baltic and Atlantic salmon are a result of their different genotypes (Nilsson et al., 2001) and the Baltic and the Atlantic salmon should then be considered as separate entities. Financial support was given by the European Commission under the FAIR Programme (Contract No. CT95-0009), by the Swedish Forestry and Agricultural Research Council to IB and by the Oscar and Lilly Lamm Foundation, the CF Lundstro¨m foundation and the Carl Trygger foundation to SL.
40 30 20 10 0
References 0
2
4
6
8
10
12 14
16
18
20
22
24
Temperature (°C) Fig. 1. Standardised growth rate O (%), standardised energy intake F (kJ g1) and energetic growth efficiency (%) of Baltic Atlantic salmon from Vindela¨lven (Sweden), in relation to temperature. Data from small (initial mean weight ¼ 8.5 g) parr tested in June (only growth data) and large (initial mean weight ¼ 37 g) parr tested in December–January are indicated with open and solid circles, respectively. Solid lines show fitted Ratkowsky models (see Forseth et al., 2001). Observed means72 SE are shown (for parameter estimates see Table 1).
To our knowledge, there is only one previous study of Baltic salmon growth and food intake in relation to temperature. Koskela et al. (1997) found the optimum temperatures for growth and food intake of salmon from the river Neva (601N, 311E) to be 15.6 and 17.8 1C, respectively, which is lower than for the Atlantic salmon (Jonsson et al., 2001) and the Baltic salmon in this study. The maximum growth rate for Neva River Baltic salmon (c ¼ 5.5% when standardised to a 1-g fish according to the protocol of Forseth et al., 2001) was considerably higher than for Atlantic salmon. A confounding factor might be that the Atlantic salmon in the study by Jonsson et al. (2001) were reared in groups while the Baltic salmon in this study and were reared singly. However, in a study by
Brett, J.R., 1979. Environmental Factors and Growth. Fish Physiology. Academic Press, New York, pp. 599–675. Efron, B., Tibshirani, R.J., 1993. An Introduction to the Bootstrap. Chapman & Hall, London. Forseth, T., Hurley, M.A., Jensen, A.J., Elliott, J.M., 2001. Functional models forgrowth and food consumption of Atlantic salmon parr, Salmo salar, from a Norwegian river. Freshwater Biol. 46, 173–186. Jonsson, B., Forseth, T., Jensen, A.J., Næsje, T.F., 2001. Thermal performance injuvenile Atlantic salmon, Salmo salar L. Funct. Ecol. 15, 701–711. Klemetsen, A., Amundsen, P.A., Dempson, J.B., Jonsson, B., Jonsson, N., O’Connell, M.F., Mortensen, E., 2003. Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus L.: a review of aspects of their life histories. Ecol. Freshwater Fish 12, 1–59. Koskela, J., Pirhonen, J., Jobling, M., 1997. Feed intake, growth rate and body composition of juvenile Baltic salmon exposed to different constant temperatures. Aquacult. Int. 5, 351–360. Larsson, S., Berglund, I., 1998. Growth and food consumption of 0+ Arctic charr fed pelleted or natural food at six different temperatures. J. Fish Biol. 52, 230–242. Larsson, S., Berglund, I., 2005. The effect of temperature on the energetic growth efficiency of Arctic charr (Salvelinus alpinus L.) from four Swedish populations. J. Therm. Biol. 30, 29–36. Larsson, S., Forseth, T., Berglund, I., Jensen, A.J., Na¨slund, I., Elliott, J.M., Jonsson, B., 2005. Thermal adaptation of Arctic charr: experimental studies of growth in eleven charr populations from Sweden, Norway and Britain. Freshwater Biol. 50, 353–368. Nilsson, J., Gross, R., Asplund, T., Dove, O., Jansson, H., Kelloniemi, J., Kohlmann, K., Loytynoja, A., Nielsen, E.E., Paaver, T., Primmer, C.R., Titov, S., Vasemagi, A., Veselov, A., Ost, T., Lumme, J., 2001.
ARTICLE IN PRESS 246
S. Larsson, I. Berglund / Journal of Thermal Biology 31 (2006) 243–246
Matrilinear phylogeography of Atlantic salmon (Salmo salar L.) in Europe and postglacial colonization of the Baltic. Mol. Ecol. 10, 89–102. Nordgarden, U., Oppedal, F., Taranger, G.L., Hemre, G.-I., Hansen, T., 2003. Seasonally changing metabolism in Atlantic salmon (Salmo salar L.) I— Growth and feed conversion ratio. Aquacult. Nutr. 9, 287–293.
Ratkowsky, D.A., Lowry, R.K., McMeekin, T.A., Stokes, A.N., Chandler, R.E., 1983. Model for bacterial culture growth rate throughout the entire biokenetic temperature ange. J. Bacteriol. 154, 1222–1226. Smith, I.P., Metcalfe, N.B., Huntingford, F.A., Kadri, S., 1993. Daily and seasonal patterns in the feeding-behavior of Atlantic salmon (Salmosalar L) in a sea cage. Aquaculture 117, 165–178.